The Swiss Federal Laboratories for Material Science and Technology (Empa) have developed a proof of principle prototype of their paper battery. Designed as an alternative to contemporary single-use batteries, the prototype has shown that the concept is functional.

Rather than the metals-intensive batteries in common use, the Empa version is predominantly constructed of paper, ink and a singular cell. It uses water as a catalyst.

The paper is formed with sodium chloride (salt) dispersed throughout it. The two shorter ends are dipped in wax and wires are attached to transport the electrons out of the battery, into a circuit. The first ink to be printed on one side contains graphite flakes, and the second, on the other side, zinc powder. These act as a cathode and anode respectively. The third ink is printed on both sides over the top of the others, it contains graphite flakes and carbon black.

To begin the reaction a small amount of water is added to the paper, dissolving the salts and releasing charged ions. As the ions disperse throughout the paper the zinc ink at the negative end releases electrons. The graphite and carbon mix ink transfers these electrons to the positive end, here being transferred to oxygen atoms in the surrounding air. This creates a stable electrical current.

Gustav Nyström says, “What’s special about our battery is that, in contrast many metal air batteries using a metal foil that is gradually consumed as the battery is depleted, our design allows [the addition of] only the amount of zinc to the ink that is actually needed for the specific application.”